Pressure operated baffle for high voltage gas operated circuit breaker

ABSTRACT

A movable baffle for the interrupter of an SF6 circuit breaker in which the baffle is movable to a position surrounding the stationary contact by gas pressure when a blast valve is opened and the circuit breaker is to be opened. The baffle, when engaging the stationary contact, defines a gas channel to conduct gas through the arc interruption region. A spring bias moves the baffle away from the stationary contact and to a favorable dielectric position when the interrupter contacts are open.

United States Patent [72] Inventors Henry G. Meier Glendale; James R. McCloud, Burbank, both of, Calif.

[2]] Appl. No. 845,375

[22] F1led July 28, 1969 [45] Patented Aug. 31, 1971 [73 Assignee I-T-E Imperial Corporation Philadelphia, Pa.

[ 54] PRESSURE OPERATED RAFFLE FOR HIGH VOLTAGE GAS OPERATED CIRCUIT BREAKER 8 Claims, 3 Drawing Figs.

[52] US. Cl 200/148 [51] Int. Cl H0111 33/80 [50] Field of Search 220/148 [56] I References Cited UNITED STATES PATENTS 3,495,057 2/1970 Golota 200/148 (B) 3,497,653 2/1970 Strom et al. 200/l48 (B) Primary Examiner-Robert S. Macon Attorney-Ostrolenk, Faber, Gerb and Soffen ABSTRACT: A movable baffle for the interrupter of an SF, circuit breaker in which the baffle is movable to a position surrounding the stationary contact by gas pressure when a blast valve is bpened and the circuit breaker is to be opened. The baffle, when engaging the stationary contact, defines a gas channel to conduct gas through the, arc,interruption region A spring bias moves the baffle away from the stationary contact and to a favorable dielectric position when the interrupter contacts are open.

PRESSURE OPERATED BAFFLE FOR HIGH VOLTAGE GAS OPERATED CIRCUIT BREAKER RELATED APPLICATIONS This application is an improvement of the structure shown in copending application Ser. No. 680,778 filed Nov. 6, 1967, in the name of John H. Golota, and assigned to the assignee of the present invention.

THE PRIOR ART Circuit interrupters of the type to which the invention applies are known and are typically shown in the above-noted application. Such interrupters are provided with a stationary nozzle contact and a movable contact which is surrounded by a movable bafile which can engage the stationary nozzle contact to define a confined gas blast path through an are drawn between the movable and stationary contacts during their separation. A blast valve which is upstream of the contacts is opened just prior to the opening of the contacts. The baffle is adapted to be withdrawn when the contacts are fully opened and the gas blast is turned off to bring it out of the high electrostatic stress region between the opened contacts.

In the past, the baffle is biased to its open position by suitable biasing springs, and is closed, with the movable contact, when the movable contact closes. That is, during the closing operation, the movable contact engages an extension on the baffle, and both drive closed to the stationary contact. During the interruption action, the gas blast action holds the baffle closed (against its opening bias) while the movable contact retracts; After the gas blast is cut off, the baffle is then moved open. It has been found that the high forces involved in the closing action can cause breakage of the baffle when the movable contact and baffle close in on the stationary contact. The present invention provides a novel baffle operating system for preventing such baffle breakage.

SUMMARY OF INVENTION In accordance with the invention, the baffle is normally in its open position by virtue of opening bias springs, and is closed, only when the contacts are to be opened, by the differential pressure of the high pressure gas used to extinguish the arc. Thus, when the contacts are closed, the baffle is open (since it is not moved closed with the movable contact). Just prior to a circuit interruption, the blast valve is opened, thereby driving the baffle closed (with moderate closing forces), thereby driving the baffle closed to define a desired path for gas flow between the separating contacts. Afterthe blast valve is closed, and the contacts are open, the baffle withdraws to its normally open position.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF INVENTION a. Background of the Invention FIGS. 1 and 2 show a typical prior art interrupter structure to which the present invention is applied. The device of FIGS. 1 and 2 is shown in copending application Ser. No. 680,778 and the disclosure of that application is.incorpor,ated herein by reference to show the entire' circuit breaker assembly which would be used with the present invention.

FIG. I shows the assembly of'a prior art interrupter assembly, and illustrates two series connected interrupters l0 and 11. interrupters and 11 are identical and will be described in detail hereinafter. The interrupters 10 and 11 are controlled by an operating mechanism, generally indicated by numeral 12, which is supported on a tank housing 13. Tank housing 13 is, in turn, carried on an elongated insulation pedestal 14 which may be carried on a high pressure gas supply at ground potential.

Each of interrupters l0 and 11 are connected at their tops to conductors which are connected in series with the circuit to be protected. The connection surrounding the tops of interrupters 10 and 11 and the insulator bushings are covered with corona shields 15 and 16. FIG. 2 shows the connection of interrupter 10 to a lower conductive end portion 17 of an insulator bushing.

An upper adapter plate 18 is provided which has a series of tapped openings therein, and alternate through openings (not shown). .The upper surface of adapter 18 then has a conical surface 31 which engages the conical lower surface 32 of insu lator 17 to permit angular adjustment of insulator 17, as shown by arrow 17a in FIG. 2. A series of bolts, such as bolt 33 having washer 34, then extend through openings, such as through-opening 28, to secure upper adapter 18 to insulator A lower adapter 35 is then provided which has a plurality of extending ears containing through-openings such as opening 36 extending from a central web 42. An annular groove 43 is cut through the web42 so that it is held by the material of the extending cars. A plurality of through-holes and aligned tapped openings such as opening 44 are then formed in the web 42, and the interior web surface is threaded by thread 50. The through openings in lower adapter 35 are then aligned with tapped openings in upper adapter 18 and suitable bolts and washers, such as bolt 51 and washer 52, shown in FIG. 1, secure shield 15 and adapter plates 18 and 35 together.

The interior thread 50 of web 42 of lower adapter 35 receives the stationary contact 53 of the interrupter. Contact 53 comprises a main body 54 having a central opening 55 which tapers outwardly to define a blast orifice. The outer diameter of body 54 is threaded with a thread 56, and an areresistant insert 57. Thread 56 of contact v5 3 is then threaded into thread 50 of lower adapter 35 and is secured therein by tightening a plurality of bolts, such as bolt 570 shown in FIG. 2, which pass through the through-openings in the lower part of web 42 and into the threaded opening 44. As these bolts are tightened, the upper and lower interior portions of web 42 tighten on thread 56 to hold contact 53 securely. Note that the axial contact position is easily controlled by threading contact 53 more or less into thread 50, as shown by arrow 58 in FIG. 2. Moreover, by providing clearance between the outer diameter of the bolts, such as bolt 51, which secure lower adapter 35 to upper adapter 18 and the corresponding through-openings, such as opening 36, lateral adjustment can be obtained for contact 53, as shown by arrow 59 in FIG. 2.

The movable contact assembly is shown in FIG. 2 and is composed of a circular cluster of contact fingers, such as fingers 60 and 66, each having generally rectangular shape. Each of the contact fingers have arc-resistant inserts secured thereto, such as inserts 72 and 73, secured to contacts 60 and 66, respectively. Each of the contact fingers have two projections, such as projections 74 and 75, for finger 60, which receive biasing leaf springs shown as leaf springs 76 and 77 for contacts 60 and 66 which bear on insulation buttons 78 and 7.9, respectively.

The-contact fingers are laid on the outer notches in a contact retainer 80, and are held on the retainer 80 by a spring retainer 81 which encircles the central exterior portions of the contacts.

A locking disk 83 having a central opening is inserted into retainer 8.0 and into engagement with the shoulder of retainer 80. A movable arcing contact 85 is then secured to locking disk 83, as by pins extendingfrom disk 83 to arcing contact 85. It will be noted that arcing contact 85 has'a bottom flange which has an outer diameter that engages the arcing contact tips of the arcing contact fingers to limit their inward collapse and to provide commutation of the arc from insert 72'to contact 85 during opening. The interior of arcing contact 85 is threaded and threadably receives the end of operating shaft 86 and is secured thereon by a suitable locking nut.

An interrupter support 88 is then provided for slidably holding the movable contact assembly. Support 88 contains a central stationary contact portion 89, the outer end of which slidably receives the lower ends of contact fingers, such as fingers 60 and 66, in slidable engagement. Central portion 89 is connected to base portion 90 by suitable webs (not shown). Two rings 107 and 108 of insulating material, shown in FIG. 2, are contained in internal grooves in the central opening 111 of central portion 89 to seal around the operating rod 86 and to provide electrical insulation betweenv rod 86 and base 90, as shown in FIG. 2. Support 88 is then fastened to support casting sections 112 and 113 (which are parts of a common casting) of FIGS. 1 and 2, as by bolts which thread into appropriate tapped openings in casting sections 112 and 113, partly shown in FIG. 1 by bolts 114 and 115. Note that the operating rod 86 passes through a suitable opening, which may be sealed, in casting section 1 12.

An interrupter tube assembly, arranged above the support 88 and enclosing the contact area is carried on a flange 116. Flange 116 comprises an extending cylindrical portion 117 secured to support 88 beneath it by bolts (not shown) extending through openings in flange 116 and respective openings in support 88, which bolts are threaded into the castings 112 and 1 l3.

An interrupter tube 122 is then secured to extension 117 in any suitable manner, where tube 122 is of glass fiber, or the like. Tube 122 then slidably receives the movable interrupter tube portion (or baffle) 123, which is movable in the direction of arrow 124, with a gasket 1250 between the surfaces of tube 122 and sliding portion 123.

The movable interrupter tube or baffle 123 comprises an outer insulation cylinder 125 and an inner lining cylinder 126 which secure, between them, an insulation lining disk 127 and baffle ring 128. The bottom of the cylinders are secured by ring 129 which has a lower lip extending below liner 126 and a plurality of pins, such as pin 130, which extend into cylinder 125.

Four pins, two of which are shown as pins 131 and 133, then extend into openings in ring 129 and are locked therein by suitable locking pins. Pins 131 and 133 are seen in FIG. 2 with the four pins disposed 90 from one another. Each of the pins have enlarged heads, such as head 135 of pin 133, which are captured in housings, such as housing 138 for pin 133. A split retainer spring disk 139 has suitable openings for receiving the four spring housings, including housing 138. Internal springs, such as spring 145 of housing 138, then, bias the housings toward the ring 129 and external springs, such as spring 148, bias plate 139 toward the ring 129.

In assembling the movable interrupter tube, it will be noted in FIG. 2 that the periphery of plate 139 is captured between adapter 116 and support 88, with ring 129 beneath shoulder 150 in stationary tube portion 122. Also, it is seen that the baffle ring lies just adjacent the lower tapered surface of contact The operating mechanism for moving operating rod 86 is best shown in FIG. ll where it is seen that the casting sections 112 and 113 have a downwardly extending portion 151. Portion 151 has two slots for passing ears 152 and 153 ofa cylindrical blast valve. The cars 152 and 153 are then connected to links 154 and 155, respectively, which are, in turn, pivotally connected to operating rods 86 for interrupters and 11 through suitable couplings 156 and 157, respectively.

The blast valve comprises a cylindrical body 158 connected to a central hub 159 by streamlined arms, such asarm 160. The ends of cylindrical body 158 are formed with annular valve disk engaging sections. The interior opening in hub 159 is provided with a thread 166. The two ears 152 and 153 then extend outward from cylindrical body 158.

Cylindrical valve body 158 then moves between an upper and lower valve seat. The upper valve seat is composed of an upper disk 167 which is secured to casting section 113 and a lower disk 168 which is bolted to disk 167 as by bolts, such as bolt 169. Disk 168 is sealed with respect to casting section 1 13 by seal ring 170 and carries a main valve seat ring 171 which cooperates with the upper end of cylindrical valve body 158. A valve retaining disk 172 is bolted to disk 168 as by bolt 173 and securely holds ring 171 in position. Disk 172 also has a buffer disk 174 bolted thereto as by bolt 175 which engages nut 176 when the valve 158 is moved upwardly.

l-Iub 159 is threaded on operating shaft 177 and is locked in place by nut 176 which is also threaded on shaft 177. Note that an annular seal 178 is contained in casting portion 112 and seals around cylinder 158 and guides the motion of cylinder 158.

A ring 180 is then secured to the bottom of casting 112, and downwardly projecting members 181 are welded to ring 180. Members 181 then support the lower valve seal for valve 158. Note that a ring 182 having a sealing ring 183 engaging ring 182 is provided with a sliding seal ring 184 which surrounds the lower portion of cylinder 158.

The bottom of members 181 carries a ring 185. Ring 185 is connected to valve disk 186 and valve retainer disk 187 by bolt means, such as bolt 188. Sealing rings 189 and 190 prevent leakage between rings 185 and 186. Ring 186 carries a main valve seat 191 which cooperates with the bottom of cylinder 158. Note that a sliding seal 192 is formed between disk 186 and shaft 177, and that a buffer 193 is connected to the top of disk 187 to receive the bottom of hub 159 when valve 158 moves down.

The ring 180 is welded to high pressure tank 13 which is composed of welded upper and lower halves 200 and 201, respectively. High pressure gas, such as air as vair and preferably sulfur hexafluoride, is then supplied to the interior of tank 13 from the central channel through insulator 14 which is appropriately connected at its bottom-to a high pressure gas source, as will be later described.

An elongated operating shaft 203, which extends coaxially with insulator 14, can be moved up and down by operating means, to be later described, which may be carried at ground, and is connected to shaft 177 by a shock-absorbing coupling.

FIG. 1 further shows a small tubular member extending downwardly and into the annular space between pedestal 14 and rod 203, and arranged so that any gas which condenses on the surface of housing 13 will flow downwardly and freely through the annular space without impinging on the insulating surfaces of members 14 and 203.

, The coupling as shown in FIG. 1 is comprised of a spring 204 captured between rings 205 and 206 at its top and bottom, and an outer cylinder 207 on its outer periphery. Ring 205 is captured beneath a shoulder in shaft 177 as shown, while ring 206 is held by nuts 208 and 209 which are threaded on the threaded bottom of shaft 177. Outer shells 210 and 211 each have threaded interiors, threaded on the outer threaded surface of cylinder 207 with extension 212 of shell 210 bear- 7 This also makes the'mechanism relatively insensitive to small dimensional changes such as produced by misalignment and temperature changes.

OPERATION OF PRIOR ART DEVICE OF FIGS. 1 AND 2 The prior art device of FlGS. 1 and 2 operates such that interrupter tube 123 is biased downwardly to an open position by spring 145 when the movable contact structure is open.

When the circuit breaker is closed, the movable contact moves up and the upper end of insert 72 picks up the movable tube or baffle 123 at liner 127 and drives the baffle against and around the stationary contact 53. This then defines a channel for movement of high pressure gas through the interior of baffie 123 and out through the opening 55 in contact 53, and thus through the separating contacts.

When the circuit breaker is to be opened, operating rod 203 moves down to open valve 158, permitting the flow of high pressure gas into the interior of the interrupter and the interior of baffie 123. Note that the pressure of this gas holds the baffle 123 closed against the force of its opening biasing springs even though the movable contact moves down and away from baffle 123. Thus, the desired gas passage for moving gas though the orifice 55 is maintained by baffle 123.

Once the valve 158 reaches valve 191, the contacts are fully open and the arc extinguished. The gas pressure is removed from baffle 123 so that it is moved downward to an open" position by its biasing springs so that it is removed from the high stress of the electrostatic field in the region between the open contacts.

It is seen that the baffle 123 is driven closed by the movable contact (or is closely followed by the movable contact) when this contact is closed, and is held in its closed position. It has been found that the high impact forces on the baffle from the movable contact can break the baffle 123.

THE INVENTION SHOWN IN FIG. 3

The present invention provides an improved drive for baffie 123 in which it is operated solely by differential pressure operating against the biasing force of the baffle opening springs so that the baffle 123 is not subject to breakage due to impact with the movable contact. The invention is shown in FIG. 3 in which parts similar to those of FIGS. 1 and 2 have similar identifying numerals. A few further differences, besides the change in the essential baffle structure are also shown in F1G.'3, and will be discussed. In FIG. 3, the structure to the left of the centerline is shown in section with'the baffle 123 open and the contacts closed. The movable contact is shown in plan view to the right of the centerline with the movable contact in its open position.

The interrupter of FIG. 3 corresponds to interrupter of FIGS. 1 and 2, and it is seen that lower adapter plate 35 receives contact 53. The movable contact assembly 300 is similar to that of FIG. 2, but is modified in a few respects. Thus, typical contact 301, corresponding to contact 66 of FIG. 1 has an integral arcing surface 302 for engaging contact 53. Note that finger contacts 303, 304 and 305 are partly shown, in the open position to the right of the centerline in FIG. 3. In addition, a circular conductive shield 306 is secured to the various contact finger biasing springs and cooperates with member 81 in FIG. 2. Arcing contact 85 is attached to rod 86 by a modified flanged body 310 in FIG. 3. In addition, a modified buffer 311 is secured to member 89 to receive the bottom of member 310 when the movable contact reaches the open position. I

In FIG. 3, a unitary sleeve 312 bolted to body 88 replaces flange 117 and member 122 of FIG. 2, where sleeve 312 has a larger diameter than member 122 of FIG. 2 to accommodate a larger diameter baffle 123.

Baffle 123 has a shortened inwardly turned lip 313, the interior diameter of which is greater than the outer diameter of contact shield 306. Thus, as contrasted to the arrangement of FIG. 2, the movable center assembly will now engage baffle 123. Baffle 123 then has an interior liner 314, and the baffle is secured to a lower plate 315 by a clamp 316. Plate 315 receives a plurality of bolts, such as bolts 317, about its periphery which have extending heads such as head 318. Spring housings, such as housing 319 in FIG. 3, are pressed against plate 315 by springs, such as spring 320, partly shown in FIG. 3, which presses between head 318 and the top of tube 319. Tube 319 is then biased against fixed plate 321 by spring 322 contained in spring guide tube 323. As in the case of FIG.

2, a plurality of such spring support elements are disposed around the peripheryof plate 315, and operate normally to bias baffle 123 downward to the open position shown in FIG. 3 (through compression springs such as spring 320).

OPERATION OF DEVICE OF FIG. 3

In operation, when the contacts are closed, as shown to the left in FIG. 3, the baffle 123 will be open due to the biasing springs, such as spring 320, which bias baffle 123 downwardly. If the breaker is to be opened, rod 86 is moved down, and, as shown in FIGS. 1 and 2, the blast valve 158 is opened. A high pressure gas then flows upwardly in the direction of arrow 330, thereby applying a differential force to baffle 123 which moves the baffle upward and against springs such as spring 320. The baffle 123 then closes against a seal 331 formed in contact 53, thereby defining a gas flow channel through orifice 55. The contacts subsequently separate and this gas flows in the region of the arc to cool and deionize the arc. When the movable contact reaches its fully open position shown to the right of the centerline in FIG. 3, the blast valve closes and the high pressure gas is cut off. Thus, baffle 123 retracts to its open position and away from the gap between the open contacts.

When the breaker is to be closed, rod 86 is moved upward and the blast valve is again opened. High pressure gas thus flows to temporarily close baffie 123 to form the desired gas channel through orifice 55. After the contacts are closed, the blast valve closes, and baffle 123 retracts to its open position. Note that in the above operation, the movable contact does not engage baffle 123 and any overtravel of the movable contact will not affect the baffle 123. Moreover, and as shown in FIG. 3 to the right of the centerline, the baffle 123 is disposed in its most favorable dielectric position when the contacts are open with its inwardly facing lip 313 generally parallel to the end of arcing contact 57. Thus, the baffle 123 generally follows an equipotential line in the open contact gap, and is subject to minimum dielectric stress.

Although this invention has been described with respect to particular embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and, therefore, the scope of this invention is limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In a high voltage gas blast circuit breaker;

a. a stationary contact having a central gas passage therethrough,

a movable contact movable between engagement and disengagement with said stationary contact,

. a movable baffle surrounding said movable contact and movable along the axis of said movable contact; one end of said movable baffle movable into sealing relation around said central gas passage of said stationary contact,

d. a blast valve connected to said movable contact for applying a high gas pressure to the interior of said movable baffle while said movable contact moves between engagement and disengagement with respect to said stationary contact,

. biasing means for biasing said movable baffle away from said stationary contact to a retracted position and to a relatively favorable dielectric position with respect to the gap formed between said stationary and movable contacts when said contacts are disengaged, f and differential pressure means on said movable baffle fo receiving said high pressure gas when said blast valve is open to move said movable baffle into said sealing relation with said central gas passage of said stationary con tact, thereby to define a closed channel through the gap between said movable and stationary contacts for carrying the flow of said high pressure gas; said baffle being moved to said retracted position when said blast valve is closed,

g. said baffle being movable independent of the position of said movable contact, whereby said baffle is normally in its said retracted position when said'contacts are closed.

2. The device of claim 1 wherein said differential pressure means includes an inwardly turned lip at the end of said movable baffle which engages said stationary contact.

3. The device of claim 1 wherein said stationary contact contains a sealing ring for receiving the end of said movable baffle.

4. The device of claim 1 wherein said baffle comprises a hollow tube of insulation material, and fixed support sleeve I means for slidably engaging and supporting the exterior surface of said baffle.

5. The device of claim 1 wherein said stationary contact includes a centrally disposed elongated tubular arcing extension facing said movable contact; said baffle having an inwardly turned lip defining said differential pressure means; said inwardly turned lip being radially spaced from and disposed adjacent the outer end of said arcing contact extension when said baffle is in its said retracted position, thereby to" be favorably disposed in the field between said movable and stationary contacts when said contacts are open. 7

6. The device of claim 5 wherein said stationary contact contains a sealing ring for receiving'the end of said movable baffle.

7. The device of claim 5 wherein said baffle comprises a hollow tube of insulation material, and fixed support sleeve means for slidably engaging and supporting the exterior surface of said bafile; said sealing ring being disposed above and on a greater diameter than the diameter of said extension.

8. The device of claim 6 wherein said bafile comprises a hollow tube of insulation material, and fixed support sleeve means for slidably engaging and supporting the exterior surface of said baffle. i 

1. In a high voltage gas blast circuit breaker; a. a stationary contact having a central gas passage therethrough, b. a movable contact movable between engagement and disengagement with said stationary contact, c. a movable baffle surrounding said movable contact and Movable along the axis of said movable contact; one end of said movable baffle movable into sealing relation around said central gas passage of said stationary contact, d. a blast valve connected to said movable contact for applying a high gas pressure to the interior of said movable baffle while said movable contact moves between engagement and disengagement with respect to said stationary contact, e. biasing means for biasing said movable baffle away from said stationary contact to a retracted position and to a relatively favorable dielectric position with respect to the gap formed between said stationary and movable contacts when said contacts are disengaged, f and differential pressure means on said movable baffle for receiving said high pressure gas when said blast valve is open to move said movable baffle into said sealing relation with said central gas passage of said stationary contact, thereby to define a closed channel through the gap between said movable and stationary contacts for carrying the flow of said high pressure gas; said baffle being moved to said retracted position when said blast valve is closed, g. said baffle being movable independent of the position of said movable contact, whereby said baffle is normally in its said retracted position when said contacts are closed.
 2. The device of claim 1 wherein said differential pressure means includes an inwardly turned lip at the end of said movable baffle which engages said stationary contact.
 3. The device of claim 1 wherein said stationary contact contains a sealing ring for receiving the end of said movable baffle.
 4. The device of claim 1 wherein said baffle comprises a hollow tube of insulation material, and fixed support sleeve means for slidably engaging and supporting the exterior surface of said baffle.
 5. The device of claim 1 wherein said stationary contact includes a centrally disposed elongated tubular arcing extension facing said movable contact; said baffle having an inwardly turned lip defining said differential pressure means; said inwardly turned lip being radially spaced from and disposed adjacent the outer end of said arcing contact extension when said baffle is in its said retracted position, thereby to be favorably disposed in the field between said movable and stationary contacts when said contacts are open.
 6. The device of claim 5 wherein said stationary contact contains a sealing ring for receiving the end of said movable baffle.
 7. The device of claim 5 wherein said baffle comprises a hollow tube of insulation material, and fixed support sleeve means for slidably engaging and supporting the exterior surface of said baffle; said sealing ring being disposed above and on a greater diameter than the diameter of said extension.
 8. The device of claim 6 wherein said baffle comprises a hollow tube of insulation material, and fixed support sleeve means for slidably engaging and supporting the exterior surface of said baffle. 